High-speed printing with continuously moving carriage



Nov. 5, 1968 L. DJCHAMNESS T' 3,408,930

HIGH-SPEED PRINTING WITH CONTINUOUSLY MOVING CARRIAGE Filed Oct. 2, 19672 Sheets-Sheet 1 m l G \25 r- 52b L. 1 2 IIJHE22 12 24' j, 2

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HIGH-SPEED PRINTING WITH CONTINUOUSLY MOVING CARRIAGE 2 Sheets-Sheet 2Filed Oct. 2, 1967 SYNC. Cl QCUIT United States Patent 3,408,930HIGH-SPEED PRINTING WITH CONTINUOUSLY MOVING CARRIAGE Leland D.Chamness, Castro Valley, and Andre F. Marion,

Berkeley, Calif., assignors to Friden, Inc., a corporation of DelawareContinuation-impart of application Ser. No. 553,961, May 31, 1966. Thisapplication Oct. 2, 1967, Ser. No. 672,137

9 Claims. (Cl. 101-93) ABSTRACT THE DISCLOSURE A high-speed serialprinter having a single print hammer and a single continuously rotatingendless character belt, both of which are mounted on a single carriagewhich moves continuously along the print line. The characterbelt rotatesabout an axis perpendicular to the direction of travel of the carriage.

This application is a continuation-in-part of our earlier filedapplication entitled High-Speed Printer, Ser. No. 553,961, filed May 31,1966, now abandoned.

Background, field of invention This invention relates to high-speedserial printers, and in particular to a printer apparatus utilizing acontinuously rotating endless character element.

Generally, printers incorporate means for carrying characters or symbolsto be imprinted upon a record medium or paper, and a print hammer forstriking selected characters. The character support may take the form ofa drum or disk, a wire, chain or flexible belt, by way of example. Inany case, it is highly desirable to achieve high printing speeds at thelowest cost, with optimum resolution and quality. In addition, theprinter apparatus should have long life capability, with a minimum ofmaintenance during its operating life.

One method of increasing the speed of a printer is through the use ofthe on-the-fly printing principle. In an impact type printer using thisprinciple, the type characters are formedson the circumference orperiphery of a rotating element, for example, a wheel or a drum, and aninked ribbon and the paper are interposed between the character elementand a print hammer. A character is printed on the paper by firing thehammer whenever a desired character passes in front of the hammer,thereby striking the paper against the continuously rotating characterelement.

In the past, such on-the-fly printers, in order to obtain great printingspeed, have utilized a plurality of print hammers and actuatingmechanisms, there being one print hammer for each print position orcolumn in a row of printed characters. Such a printing mechanism,however, is obviously rather expensive. Accordingly, the cost cannot bejustified for small systems, for example, dark-type calculators, whereinprinting rates slower than those obtainable with a parallel print-outmay be tolerated.

In order to reduce the cost of the 'on-the-fly printing mechanisms,printers which operate in a serial mode have been proposed and built. Insuch serial type printers, a single continuously rotating characterelement and a single hammer are moved in unison along the print line,either step by step or continuously, and the desired characters areprinted out in sequence. Printers utilizing the former method of movingthe hammer and print wheel along the print line suffer from problems ofcost and maintenance due to the mechanical mechanism necessary toprovide the step by step motion of the carriage, and/or a decrease ofprinting speed. Serial on-the-fly printers 3,408,930 Patented Nov. 5,1968 using the continuous motion of the carriage along the print line,on the other hand, generally require that the characters on thecharacter element be arranged in a complex geometrical pattern in orderto compensate for the continuous movement.

Summary of invention The instant invention overcomes the problems of theprior art high-speed on-the-fly serial printers, byproviding arelatively simple printer of the continuous movement type having aminimum of movable parts and a relatively simple character arrangementon the character element. Y

Briefly, a high-speed serial printing apparatus, according to theinvention, comprises a carriage, having mounted thereon an endlesscharacter element and a single print hammer, which is moved in acontinuous-motion in the direction of a print line. The endlesscharacter element, i.e., a flexible belt, is mounted for rotation aboutan axis substantially perpendicular to the travel axis of the carriagealong the print line so that all of the characters on the element arepresented to each print position on the record medium. Preferably, theportion of the character element adjacent the hammer rotates in adirection opposite to the direction of movement of the carriage. Meansare also provided for sensing the instantaneous position of thecharacters on the element, and for firing the hammer when a selectedcharacter passes a print position.

Brief description of drawings The invention will be described in greaterdetail with reference to the drawings in which:

FIG. 1 is a simplified plan view of the printer apparatus of thisinvention;

FIG. 2 is a sectional view taken along the plane indicated by the line2-2 of FIG. 1;

FIG. 3 is an enlarged view of a number of characters in a line of printillustrating the dimensions between the various printed characters onthe paper;

FIG. 4 is an enlarged view of a portion of a character element showingthe dimensions between the various characters and character positionsthereon;

FIG. 5 is a perspective view of the novel apparatus;

FGI. 6 is a top plan view of the printer apparatus illus trated in FIG.5; and

FIG. 7 is a side elevational view taken along the planes indicated alongthe lines 7-7 of FIG. 6.

Description of preferred embodiments Similar numerals refer to similarelements throughout the drawings.

With reference to FIGS. 1 and 2 of the drawings, a high-speed printerapparatus in accordance with this invention comprises a carriage 10 onwhich is mounted an endless character element 12 and a print hammerassembly 14 for conjoint travel. The carriage 10 is moved by drive means16 coupled to a rotary threaded shaft 18 on which the carriage rides ina well known manner. The character element 12, which as shown, is aflexible band or belt, e.g., a metal band, having embossed charracters20 formed on the circumference or periphery thereof, is rotated by meansof adriven pulley wheel 22 and an idler 24 about an axis substantiallyperpendicular to the travel axis of the carriage 10, i.e., perpendicularto the axis of shaft 18. The pulleys 22 and 24 are preferably providedwith sprockets (not shown) which mate With correspondingly spaced holesor apertures in the character belt in order to prevent the belt fromslipping when it is contacted by the hammer. The use of a flexible beltpermits the hammer 14 to be placed within the loop formed by the belt,whereby all of the moving parts of the printer, i.e., hammer, belt andcarriage may h juxtaposed only one surface of the paper. This has theadvantage of providing a relatively simple, compact and inexpensiveprinter mechanism. Preferably, the character element 12 is rotated sothat the portion of the element adjacent the hammer 14 moves in adirection opposite to that of the carriage 10. In the figures, whereinthe direction of movement of the carriage is indicated as from left toright, the character element 12 is rotated in a counter-clockwisedirection. This has the effect of reducing the relative velocity betweenthe characters 20 and the paper or printing record medium 26, andthereby allows for higher velocities of the belt and higher printingspeeds.

Although not shown in FIGS. 1 and 2, it is to be understood that themotion of the character element 12 must be synchronized with that of therotary thread 18 in order that printing of the desired character may beaccomplished at the proper print positions. The synchronism may beaccomplished by any means Well known in the art, for example, by meansof an external monitoring or synchronizing circuit, or by providing apositive mechanical drive connection, for example, a gear or a chain andsprocket drive, betweent he drive means for the carriage 10 and thedrive pulley 22.

During operation of the apparatus, the carriage 10 is moved continuouslyin the direction of printing by the rotary thread 18. The carriage 10may be engaged with the thread by means of a detent pin, by way ofexample, which is seated in the groove of the thread during the forwarddrive of the carriage in the print mode; and is disengaged from thethread when the carriage is being retracted to its starting or homeposition to enable the printing of a subsequent line of print.Retraction of the carriage at the end of each print cycle may beachieved in any known manner, e.g., by a resilient spring which islinked to the carriage and is progressively tensed as the carriage ismoved during the print mode. A carriage drive of this type is disclosedin copending US. patent application Ser. No. 663,292, filed Aug. 25,1967 which is a continuation-in-part of US. patent application Ser. No.528,501, filed Feb. 18, 1966 now abandoned, in behalf of the sameinventors and assigned to the same assignee as for this application.

To achieve printing on the record medium or paper 26, the belt 12 isdisposed between the paper and hammer 14, and the paper is positionedbetween the belt 12 and a platen 28. A ribbon 30 carried by spools 32aand 32b is located between the belt 12 and paper 26; or alternatively, aself-inked paper may be employed. The printing of the desired charactersis accomplished by firing the hammer to strike the selected characterwhen the character arrives at print position. Such coincidence may bedetermined by means of timing marks 34, e.g., apertures or magneticspots (FIG. 2) corresponding to each character and an index or referencemark (not shown), all formed at predetermined positions on the belt. Thetiming marks may be sensed optically or electrically, and countedsuccessfully for each cycle of belt revolution, whereby theinstantaneous position of each character or symbol may be established.Other well-known means for selecting the characters to be printed may beutilized. For example, the timing marks need not be located on the beltbut may, if desired, be located on any other surface, e.g., the top ofpulley 22, whichmoves in synchronism with the belt.

To determine the relationship of the various parameters of the printingsystem, let us assume that the counterclockwise rotational velocity ofthe belt 12 is V and that the carriage moves at a speed V in the forwardor print direction. Therefore, the apparent velocity of any point on thecharacter belt, as seen at the print position adjacent to the hammer,may be defined as V V If we wish to print R characters per second, thenall the characters must traverse the print position in l/R seconds; andif we have N possible equally spaced character positions on thecharacter element, each of which is to be scanned for each printposition, the time interval between any two character positions is l/RNseconds. During such interval, the apparent displacement of a characteron the belt is d=(V -V )1/RN and the displacement of the carriage 10 iss= V (l/RN) If, as shown in FIG. 3, eachcharacter on the paper occupiesa space having a standard widthw, and the blank space between charactersis designated as w, then w-l-w describes the distance P between printpositions. Thus, for each revolution of the belt accomplished in l/Rseconds, the carriage velocity is V =PI R inches per second; or thecarriage displacement per character position movement past a print'position is s='P/N inches.

At this point, it should be noted that although theoretically all of thecharacter positions on the character element or belt 12 may containcharacters, and although such an arrangement is possible if the printingrate is very slow, in a practical application, the number of characterpositions on the character belt 12 must be greater than the number ofcharacters in the group or sequence from which it is desired to selectone character for printing in a particular print position. For example,if the group of characters on the character element represents thenumeral 0 to 9, then the character element 12 should, for example,contain twenty equally spaced character positions. These additionalcharacter positions are required because of the finite time required tocock the hammer 14 between successive printing positions. It should benoted that in the above example, wherein it is stated that there aretwenty character positions on the character element, that an additionalsequence of characters may be placed in the remaining ten characterpositions. In such 'a case, in order to allow for cocking of the hammer,a space or unused print position on the paper would have to be providedwhenever two successive characters were selected from different groupsor sequences.

Returning now to the consideration of the parameters of the printer, itcan easily be seen that the total displacement of the carriage measuredbetween the first and last character of a group or sequence characterson the belt, wherein L represents the number of characters in thesequence, and all successive characters in the sequence are located inadjacent character positions, is equal to P XL In order for the hammerto be able to print any of the characters in any sequence at each printposition, the hammer width It should be In order that the hammer not beable to hit two characters at the same time, the minimum spacing a (FIG.4) between any two consecutive characters on the belt must equal thehammer width 11 plus some clearance K, e.g., .005 inch. Thisrelationship may be expressed as Since the carriage is continuallymoving, it is necessary that after each complete revolution of the belt,the first character of the group must appear at the next print positionor column. Therefore, as shown in FIG. 4, the distance between the lastand first character positions on the belt must be increased by an amountequal to P (the distance between print positions) to achieve thisalignment at each print position.

p In view of the above relationships, it may be determined that the beltlength b is b=(w+ +K)N+P and the belt velocity is Q I I LP V w+ +K)N+P]Rinches per second.

Turning now to the spacing of the timing marks 34, although anyarrangement which will identify the various character positions may beused, preferably N equally spaced timingmarks are provided, there beingone timing mark corresponding to each character position. The distance dbetween timing marks should therefore be equal to the belt lengthdivided by the number of character positions or t 1 t 1 A particularembodiment of this invention is shown in FIGS. 5, 6 and 7, wherein thecarriage 10 houses a drive motor 36 which is coupled to a drive wheel38. The wheel 38, in turn, is coupled by a belt 40 to the driven pulley22. The endless character belt 12 is looped around the pulley 22 and theidler 24, for counter-clockwise rotation, in juxtaposition to the printhammer 14 and the paper 26. Since, as illustrated, the drive linkbetween the pulleys 22 and 38 is not of a positive nature, in order toprovide synchronism between the rotation of the belt and the movement ofthe carriage, a synchronizing circuit 35 is shown. A spring 27(partially shown) is provided to return the carriage 10 to its homeposition after the completion of a line of print.

In operation, a source of power 44 energizes the drive motor 36 therebyproviding a rotational motion to the character belt 12. Simultaneously,the carriage drive 16 rotates the threaded shaft 18 whereby the carriage10 is transported axially relative to the shaft and the platen 28 alonga guide 25. A hammer actuator circuit'46 serves to fire the hammer atselected times so that predetermined characters are imprinted on thepaper 26, in a manner well known in the printing art. The power source44 and hammer actuator 46 are depicted as being connected to electricalwipers 48 that feed the energizing signals to the motor and hammer,respectively.

One embodiment of the novel printer of this invention employs twentytotal characters, including ten numerals and ten symbols on thecharacter belt. With a carriage velocity of three inches per second, anda spacing of approximately .135 inch between the type characters on thebelt, a print speed of thirty characters per second is realized.

The scope of the invention is not limited to the particular parametersand values set forth above. For example, the belt may bear alphabetic ornumerical characters, separately or in combination. Also, the velocitiesof the carriage and belt may be varied to satisfy the relationships setforth above.

It should be noted that although the serial printing arrangementspecifically described is theoretically applicable to a character beltcontaining any number of characters, that as a practical matter if thenumber of characters is too large, the print rate may have to be reducedto an undesirable value. This is due to the fact that the print rate islimited by the necessity of the belt making a complete revolution perprint position and the finite time required to strike and imprint asatisfactory character on the paper. Accordingly, in such cases, it isto be understood that the invention can equally well be applied to amore complex printing arrangement wherein a plurality of verticallydisplaced rows of characters are formed on the character belt. Ofcourse, in such a printer, means capable of selectively shifting thecharacter belt in a vertical plane during the time that the hammer isbeing cocked must be provided. Such means are, however, well known inthe art, for example, see US. Patent 3,168,182, issued Feb. 2, 1965.

There has been described herein a novel high-speed printer, wherein anendless belt carries characters to be presented to a hammer at a printposition, for selective printing on a paper. Both the belt and hammerare moved at a substantially constant speed relative to the paper bymeans of a common carriage. The apparatus affords a simple, inexpensiveconfiguration with a minimum of parts, and is characterizedby low costof manufacture andmaintenance.

It is to be understood that various changes and modifications of thepreferred embodiment can be made without departing from the spirit ofthe invention. Accordingly, the invention is to be limited only asrecited in the following claims.

What is claimed is:

1. A high-speed printer apparatus adapted for serially recordingselected characters along a print line of a record medium comprising:

a carriage adapted for continuous travel along a predetermined printline;

an endless character element comprised of a flexible belt forming aclosed loop, said belt being supported by said carriage and mounted forrotation about an axis substantially perpendicular to the travel axis ofsaid carriage;

a single print hammer mounted on said carriage and disposed adjacent toa portion of said element for imprinting selected charatcers on saidrecord medium;

means for moving said carriage conjointly with said element and saidhammer, in a continuous motion in the direction of the print line;

means for moving the portion of said element adjacent to said hammer ina direction opposite to that of said carriage during line printing;

means for rotating said element in synchronism with the movement of saidcarriage along said print line so that all of the characters on theelement are successively presented to each print position in said print'line;

means for sensing the instantaneous position of the characters on saidelement; and

means for firing said hammer when a selected character is presented to adesired print position on said record medium.

2. A high-speed printer apparatus as in claim 1 wherein said hammer,said belt and said carriage are all disposed in juxtaposition to onesurface of the record medium on which printing is effected, and whereinsaid hammer is positioned within the loop formed by said belt.

3. A high-speed printer apparatus as in claim 1 Wherein the periphery ofsaid character element is subdivided into a plurality of characterpositions at least some of which contain characters, the spacing betweenadjacent character positions, other than the spacing between the lastand first character positions being increased by a distance equal to thedistance between adjacent print positions in a print line on said recordmedium.

4. A high-speed printer apparatus as in claim 3 wherein all of thecharacters in any sequence are located in adjacent character positionson said character elements, and wherein said hammer has a width equal toP is equal to the distance between adjacent print positions on saidrecord medium, N is equal to the total number of character positions onsaid character element, and L is equal to the number of characters inany sequence which can be printed in one print position.

5. A high-speed printer apparatus as in claim 3 wherein said sensingmeans comprises a plurality of timing marks spaced at predeterminedintervals for identifying the characters on said character element. 1

6. A high-speed printer apparatus as in claim 5 where in said timingmarks are equally spaced about the circumference of said characterelement, there being one timing mark corresponding to each characterposition on said character element.

7. Ahigh-speed printer apparatus as in claim 6 Wherein the portion .ofsaid character element adjacent to said hammer moves in a directionopposite to that of said carriage during line printing.

v 8. A high-speed printer apparatus as in claim 7 Wherein said hammer,said belt andsaid carriage are all disposed in juxtaposition to onesurface of the record medium on which printing is effected, and whereinsaid hammer is positioned within the loop for-med by said belt.

9. A high-speed printer apparatus as in claim 4 Wherein said sensingmeans comprises a plurality of equally spaced timing marks foridentifying the characters on said character element, there being onetiming mark corresponding to each character position on said characterelement.

References Cited UNITED STATES PATENTS 2,831,424 4/1958 MacDonald e-101-93 2,843,243 7/1958 Masterson 'l0l93' X 2,936,704 "5/1960' Hense 1-i 101 93 3,041,965 7/1962 Sasaki 101 111X 3,007,399 11/1961 Sasaki etal. 101 93 3,115,092 12/1963 Sasaki 101 93 3,164,084 1/1965- Paige 2-101 93 ROBERT E. PULFREY, Primary Examiner.

E S. BURR, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,408,930 November 5, 1968 Leland D. Chamness et a1.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 1, line 58, "dark-type" should read desk-type Column 2, line 21,after "riage" insert ,and is rotated in synchronism with the movement ofthe carriage line 44, FGI." should read FIG. Column 3, line 6, after"adjacent" insert to line 24, "betweent he" should read between the line58, "successfully" should read successively Signed and sealed this 17thday of March 1970.

SEAL) IteSlZ iward M. Fletcher, Jr. E.

ttesting Officer Commissioner of Patents

